Mariner 3 was part of the Mariner series of flyby spacecraft. These vehicles were designed for planetary flyby imaging. The flyby mode means that the vehicle was not designed to attain an orbit around the planet it was photographing, needles to say that all the images obtained of Mars, Mercury, and Venus by this series of spacecraft were taken during the duration of the planetary flyby. Once the flyby was concluded and the images were sent back to mission control, the mission was over unless the vehicle was designed to make several flybys.
In the case of flyby missions of several targets or planets to photograph, the trajectory of the spacecraft is planned out in such a way that it will put the vehicle in a position where it can utilize the gravitational field of a planet as a slingshot to propel it towards another celestial body. This type of mission design in which the flyby vehicle is able to send images from different celestial bodies is the most economically efficient type of mission design, because once launched the flyby spacecraft can not be recuperated for another mission.
The importance of the Mariner series in the history of space exploration is given by the images they sent back to Earth from the planets of Venus, Mercury, and Mars. Inside this series of flyby probes, the Mariner 3 is important, because it was the first American attempt to obtain images of the red planet.
As a result of technical difficulties in this probe, communication between it and mission control was lost before it arrived at Mars. The Mariner 3, which was launched on May 11, 1964, never fulfilled its mission. Although the loss of this probe was a set back to the American exploration of Mars, the technical analisys of what went wrong with the mission aided the success of the future Mariner missions.